The present invention relates to magnetic tape read/write heads. More particularly, it relates to a magnetic tape head assembly adapted to facilitate lateral movement of a read/write element relative to other head assembly components.
Magnetic tape systems for recording, reproducing, and/or erasing magnetic information in a linear tape system generally consists of a magnetic tape traveling along a magnetic head assembly. The magnetic head assembly includes a magnetic head that provides a surface (typically contoured) for guiding the magnetic tape across one or more read/write elements otherwise maintained by the head. A common concern associated with these systems is the formation of an air bearing between the tape and the magnetic head. This air bearing can cause hydrodynamic lift of the tape relative to the magnetic head, leading to performance deterioration. The primary consequences of a higher tape fly height are a decrease in read amplitude and an upward shift in the peak write current. Conversely, the read amplitude increases as the fly height decreases. In light of these concerns, substantial efforts have been made to design features into the magnetic head that remove entrained air and/or minimize air bearing formation.
Intimate contact between the tape and the magnetic head at the interface is typically increased by a combination of greater tape tension across the magnetic head and more penetration of the magnetic head into the tape. Another approach to minimizing fly height on cylindrical magnetic heads is to incorporate bleed slots. Bleed slots are grooves in the contoured surface of the magnetic head. As the tape moves across the head, the bleed slots help to channel entrained air away from the head-to-tape interface, thus reducing the height distribution of the layer of air. Thus, bleed slots function in a manner that is analogous to treads on a tire. Just as the tire treads help to channel water away from the tire surface to prevent hydroplaning, bleed slots help to channel away air from the head contour surface to minimize head-to-tape separation. Alternatively, and/or in addition, an ambient pressure head contour has been suggested in which a substantially square edge is introduced into the tape path for generating a subambient condition as the tape interfaces with the edge. An example of this approach is provided in U.S. Pat. No. 6,122,147, the teachings of which are incorporated herein by reference.
Regardless of the exact design techniques implemented to reduce hydrodynamic lift, other concerns may arise. In particular, most magnetic tapes provide a series of parallel tracks to which data is written. The read/write heads maintained by the magnetic head assembly must be moved quickly and positioned over particular data tracks as data is read or recorded. The head must move in a lateral fashion (perpendicular to tape movement) to move the read/write element from track to track. Further, servo control systems are often employed to properly position the read/write elements in the translating direction. A designated element on the magnetic head (e.g., a magnetic servo read head) “follows” a servo track on the tape to properly position the magnetic head relative to the tape. Thus, when the tape moves laterally, the magnetic head must also move laterally, dictated by the servo track/servo head interface. Thus, it is known to provide magnetic head assemblies with an actuator that laterally translates the head itself. Unfortunately, due to the extremely low fly heights achieved with various magnetic head assembly designs, lateral movement of the head may undesirably “drag” the tape in a lateral fashion as well.
For example, FIG. 1 provides a schematic illustration of a magnetic head 10 in conjunction with a tape 12 (for ease of illustration, the tape 12 is illustrated as being transparent so that components “behind” the tape 12 can be viewed). The magnetic head 10 includes a front face 14 at which read/write elements 16 are located. Further, air bleed slots 18 are formed at opposite sides of the read/write elements 16. The magnetic head 10 is laterally moveable relative to the tape 12 (shown by arrows in FIG. 1), driven by an actuator mechanism (not shown). The air bleed slots 18 reduce the air bearing between the tape 12 and the front face 14. Due to this reduction in fly height, lateral movement of the magnetic head 10 during a track access operation may drag the tape 12 in a similar lateral fashion, possibly leading to performance errors.
Reduction of the fly height between a tape and a magnetic head is highly desirable. However, in achieving this goal, other performance concerns may arise due to the magnetic head imparting lateral movement onto the tape. Therefore, a need exists for a magnetic head assembly configured to minimize the propensity of the magnetic head to “drag” the tape during track access operations.